1. Field of Invention
The present invention relates in general to the field of electrostatic ink jet printers. More particularly, the present invention relates to a disposable ink jet cartridge which forms part of a printer head which is mounted to move transversely back and forth across the width of a recording paper. Still more particularly, the present invention relates to an ink jet printer in which a replaceable cartridge contains not only the ink supply but also the ink jet itself.
2. Prior Art
Prior Art electrostatic ink jet printing systems include an ink jet nozzle, a supply of conductive ink, a metallized surface upon which recording paper is placed, and a high voltage supply connected between the conductive ink and the metallized surface. Upon application of the voltage differential, the ink is drawn from the ink jet nozzle toward the metallized surface. Since the paper is interposed between the ink jet nozzle and the metallized surface, the ink is deposited on the paper so long as the voltage is applied. Thus either the paper, the ink jet nozzle, or both have to be moved in order to print any comprehensive information.
Many problems exist in prior art electrostatic ink jet printing systems. For example, since the reservoir containing the ink supply has to be periodically refilled, the reservoir must include an opening means for adding additional ink. Oftentimes, during refilling, outside contaminents enter the opening along with the ink. Also, the container for storing the refill supply of ink may include dried ink residue which can be introduced to the system when the reservoir is refilled. The introduction of such contaminents to the ink supply reservoir often results in clogging of the ink jet nozzle. Further, the task of refilling the ink reservoir is a messy job.
Prior art systems exhibit additional problems due to variations in the level of ink in the supply reservoir. These variations cause changes in the ink head pressure to the jet nozzle and result in variations in the density and quality of the printing produced.